Can't get a 556A1to group | SIG Sauer 556 Forum

Can't get a 556A1to group

Discussion in '556 Discussions' started by sherpa1d, Jun 9, 2014.

  1. sherpa1d

    sherpa1d New Member

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    First a quick bit about me; I'm a 12-year active duty Staff Sergeant in the Army. I'm not an expert shooter by any means but I can zero my M4 with iron sites in 9 to 12 rounds with all groups in a 1 inch diameter or less at 25-meters and I'm pretty good at coaching others through zeroing and qualifying as well.

    My problem is my dad got a Sig 556 A1, 16-inch barrel, fix front site and the diopter rear site. I went to help zero it for him and I can't get crap for groups. We were shooting off a table with sandbags at approx 25 meters at an M4 zero targets. Only once did I get a 2.5inch group, the group placement was never consistent, one would be lower left about 4-in off center, make some adjustments and it would be close, shoot again with no adjustments and it would be off low right off the paper. I only even attempted to make adjustments for the hell of it because I never got a truegroup consistent enough to adjust from.

    I'll admit I've never used these type of sites before, but heck, if I'm keeping the same site picture my grouping should be consistent. I don't want to go running and say manufacturer error, I know Sig makes good stuff.
     
  2. Bosley

    Bosley Active Member

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    556 a1? is this something someone put together? i think there's only a 556 and a 551-a1.

    you should be able to get a reasonable group at 25m, but i've found that they don't like lc193s--they seem to be all over the place w/no rhyme nor reason. get a box of a few different brands of ammo and try them to find out what they like and do the bbl break in, copper solvent/rod/swab ever 5 shots, then 10 until about 70 or so i'd guess.

    fwiw, i have two of the older ERs w/swiss parts and tried to make a scope worth it on them, but they aren't. mine are fist sized grouping at 50, then at 100 pie tin depending upon what ammo i use. i'm ok w/it being a short range banger and the extra front weight/folding stock helps with that.
     
  3. shotdown61

    shotdown61 Active Member

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    You might want to check to see if the rail is tight.The screws have been known to back off.
    Take out one at a time and just use blue lock tight on the screws.Just do it now because it will happen.Trust me

    Also the diopters have been know to loosen up also.Make sure when turning it is tight and does not feel like it will try to move back and forth.
     
  4. sherpa1d

    sherpa1d New Member

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    Well, that solves one un answered question. Before going out I looked up the 556 and everything said that it would work with my GI mags and this one did not. So, I just checked and sure enough it is a 551 A1. Guess it is funny when you expect one thing you don't fully take notice. I saw the rifle a few months ago and just assumed 556 then we went to fire it and noticed the A1 but nothing else ( just excited to fire it)

    I did check the sites and everything seems to be tight. On the diopter site on the hight adjustment there feels like there is a little play but didn't seem like it was something to throw it off. I did not do a break in, just started trying to group and I did not clean between any number of shots. I did clean and lube before we took it out and did a cleaning after we gave up after about 30 rounds. I did read some people say they are touchy with light weight rounds, i do not know what weight he had, but they were Federal 5.56 ball. Thanks!
     
  5. Bosley

    Bosley Active Member

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    yup, like cwac said, check the rails. also, if it's a sig mfgr diopter, i've heard those aren't very good. i don't run them, but iirc, the hk low ghost ring rears will work and you should be familiar with them.
    should be fun to shoot. you'll get a kick out of this when trying out different ammo, it'll throw each in their own group. shoot three different loads and you'll have three different piles of brass. surprisingly pressure sensitive.
     

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